Transport trailer liftgate apparatus and method of operating the same

ABSTRACT

A liftgate apparatus may include a plurality of vertical tracks attached to a rear of a trailer, each of the plurality of vertical tracks including a vertical roller chain. Tops of the plurality of vertical tracks intersect horizontal hollow structural tubes which include hydraulic cylinders. The apparatus may also include at least one bar attached to a bottom of each vertical roller chain and attached to sets of rolling wheels configured to move the at least one bar vertically inside the plurality of vertical tracks and a plurality of hinges attached to a lower end of the at least one bar and attached to a base of a liftgate, wherein the vertical roller chain lifts the at least one bar and the liftgate at hinged points. The apparatus may also include a plurality of types of link chains, wherein a first type of the link chains supports the liftgate in a closed position and the first type is affixed to the top of the at least one bar and to the liftgate, and wherein a second type of the link chains is affixed to the top of the vertical roller chain and to mid sections of the liftgate. The apparatus may further include a plurality of sprockets connected via a shaft, wherein the vertical roller chain travels over at least one of plurality of sprockets and connects the hydraulic cylinders to the least one bar, thereby moving the at least one bar and the attached liftgate in a synchronized manner.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention is directed to liftgates apparatuses.

2. Description of the Related Art

Liftgates may be attached to vehicle trailers or other forms of vehiclecargo holds to assist with loading and unloading. In general, liftgateapparatuses include a platform or deck and a motorized system that isused to move the platform. There are several types of liftgateapparatuses, including a rotating platform apparatus and column typelift apparatuses which include rod screw type lift apparatuses andsliding bar column lift apparatuses.

The rotating platform apparatus may include a relatively small platformwhich, in the stored position, may serve as the rear enclosure for thevehicle, may fold up behind the rear enclosure, or may fold upunderneath the back of the vehicle. Its vertical height limitation isusually the height of the bed of the trailer and is approximately fourfeet above ground level. Typically, this type of liftgate apparatus mayinclude hydraulic cylinders hooked to control arms or levers. Thus, thistype of liftgate apparatus is very limited in its vertical capabilities.Furthermore, the relatively small “footprint” or size of the platformmeans that large items, for example, automobiles, cannot be placed onthe platform to be raised.

Column type liftgate apparatuses typically use hollow columns, placedvertically, one on each side of the back of the vehicle. Unlike therotating platform apparatus, the column type liftgate apparatuses may beraised to as much as ten feet above ground level. The rod screw typeliftgate apparatuses may include a machined rod screw placed verticallyinside the column and which can be turned clockwise or counterclockwise.Grooves may be machined in the rod screw along its length, giving it theappearance of a barber pole. Ball joints with similar grooves may befitted inside the rod screw grooves so that as the rod turns clockwiseor counter-clockwise, the ball joints may move up and down. The platformmay be attached to this ball joint and thus moves vertically as the balljoint moves up and down. A major drawback of this type of liftgateapparatus is price. This type of liftgate apparatus also requiresskilled personnel for operation.

Sliding bar column liftgate apparatuses replace the rod screw with asliding bar approximately five feet long in each column. These slidingbars may move vertically inside the hollow column by means of frictionslides or rollers. They are typically attached to hydraulic cylindersone of each side, mounted vertically inside the columns. As thehydraulic cylinders extend, because they are attached to the slidingbars, they raise or lower the sliding bars which are also attached via ahinge to the liftgate. With telescoping cylinders, this type of liftgatecan reach heights of approximately eight feet above ground level. Two ormore people are typically required to open and close this device.Because the slide bars of this type of liftgate extend beyond the roofof the attached vehicle, one side tends to get ahead of the othercausing jamming. Furthermore, with the cylinders in the rear, this typeof liftgate can add 12 inches or more to the length of the attachedvehicle. There are also problems typically associated with maintenanceand access of these types of apparatuses.

With traditional liftgates of both screw and slide bar types, theliftgate must be rotated into position underneath an overhanging roof,then raised vertically against a rubber or similar type seal so that theroof and seal can prevent air or rain leakage to the inside of thevehicle. Because some of these prior art devices utilize friction guidesbeside the slide bars, friction is created by these guides or spacers.As a result, in these prior art devices the liftgate may stop movingjust before it is fully closed and the liftgate cannot be opened orclosed without application of physical force. Therefore, when beingclosed, these prior art devices require physical force by one or moremen to push the gate closed as another individual works the hydrauliccontrols to raise the gate under the overhanging roof. To open the gate,men must go inside the truck/trailer and push the gate outward from theinside after it is lowered out from under the overhanging roof. Thus, inthese prior art devices a single individual cannot operate theseliftgates.

SUMMARY OF THE INVENTION

Embodiments of the present invention may be directed to a liftgateapparatus, comprising a plurality of vertical tracks attached to a rearof a trailer, each of the plurality of vertical tracks including avertical roller chain. Tops of the plurality of vertical tracksintersect horizontal hollow structural tubes which include hydrauliccylinders. The apparatus may also include at least one bar attached to abottom of each vertical roller chain and attached to sets of rollingwheels configured to move the at least one bar vertically inside theplurality of vertical tracks and a plurality of hinges attached to alower end of the at least one bar and attached to a base of a liftgate,wherein the vertical roller chain lifts the at least one bar and theliftgate at hinged points. The apparatus may also include a plurality oftypes of link chains, wherein a first type of the link chains supportsthe liftgate in a closed position and the first type is affixed to thetop of the at least one bar and to the liftgate, and wherein a secondtype of the link chains is affixed to the top of the vertical rollerchain and to mid sections of the liftgate. The apparatus may furtherinclude a plurality of sprockets connected via a shaft, wherein thevertical roller chain travels over at least one of plurality ofsprockets and connects the hydraulic cylinders to the least one bar,thereby moving the at least one bar and the attached liftgate in asynchronized manner.

Embodiments of the invention may also be directed to a method of openingand operating a liftgate of an apparatus. The method may includereleasing a set of mechanical latches via a plurality of sprocketsconnected via a shaft, wherein vertical roller chains travel over atleast one of plurality of sprockets and connect hydraulic cylinders toleast one bar configured to move the liftgate into a horizontalposition; engaging the hydraulic cylinders and pushing the liftgateoutward at the top by levers which are activated as the latches arereleased; as the liftgate moves into a horizontal position, slackening afirst set of link chains which supports the liftgate in a closedposition and which is affixed to the top of the at least one bar and tothe liftgate; tightening a second set of link chains affixed to the topof the vertical roller chains and to mid sections of the liftgate as theliftgate reaches the horizontal position; and moving the liftgate usingthe hydraulic cylinders.

Embodiments of the invention may also be directed to a method of closinga liftgate of an apparatus. The method may include vertically moving theliftgate and attaching a first set of link chains which supports theliftgate in a closed position and which is affixed to the top of atleast one bar and to the liftgate, wherein the bar is connected to theliftgate via hinged points; releasing hydraulic pressure via verticalroller chains which are attached to the at least one bar to cause theliftgate to move from horizontal to a vertical position; and upon theliftgate reaching a vertical position, tripping latches and a rain capinto position to prevent the liftgate from opening.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an embodiment of the inventive liftgate apparatus;

FIG. 2 illustrates an embodiment of a shaft used in embodiments of theinvention;

FIG. 3 illustrates an embodiment of a rain guard/latch assembly used inembodiments of the invention:

FIG. 4 further illustrates an embodiment of the liftgate apparatus,wherein the liftgate which is being opened is nearing full horizontal“platform” position;

FIG. 5 illustrates an embodiment of the liftgate apparatus, wherein theliftgate is in a full horizontal “platform” position;

FIG. 6 further illustrates an embodiment of the liftgate apparatus,wherein the liftgate is in the full horizontal or platform position;

FIG. 7 illustrates an embodiment of the invention, wherein the liftgateis being, prepared to be used as a ramp; and

FIG. 8 illustrates an embodiment of the liftgate apparatus, wherein theliftgate is being closed.

DETAILED DESCRIPTION OF EMBODIMENTS

Embodiments of the present invention may incorporate embodiments ofliftgate apparatuses that may rotate from a vertical plane to ahorizontal plane and then move as a horizontal platform vertically fromthe ground level up to first and second deck levels of an attachedtrailer. Embodiments of the liftgate apparatus can also be configured toserve as a ramp to load vehicles into the lower deck level of theattached trailer.

FIG. 1 illustrates an embodiment of the inventive liftgate apparatus.FIG. 1 shows features of the liftgate apparatus as seen from the rightside of the rear of the trailer. As would be evident to one skilled inthe art, that each of the components shown on the right side of thetrailer may also be provided on the left side of the trailer. Accordingto an embodiment of the invention, two vertical tracks 102 may beattached to the rear of a trailer, one track on each end of the trailer.Inside each track may be an industrial roller chain 106 which may extendvertically. The bottom of chain 106 may be attached to the upper end ofa steel bar 108. Also attached to bar 108 may be multiple sets ofrolling wheels, called trolleys. The trolleys may allow bar 108 to movevertically inside tracks 102 without friction.

On the lower end of steel bar 108 may be a full width hinge 116 whichmay be attached to the base of the liftgate 110. The movable steel bar108 may be approximately one inch wide by five feet long. A set ofdiagonal link chains 112 may be permanently affixed to the top of bar108. The other end of chains 112 may be attached to liftgate 110 somedistance out from hinge points 116 that connect the liftgate and bar 108via hinges. This creates a triangle between the top of bar 108 andliftgate 110 which has its hinge attached permanently to the bottom ofthe bar.

The top of vertical tracks 102 may intersect horizontal hollowstructural tubes or headers 104 which may run forward along the top ofthe trailer. Inside these tubes may be hydraulic cylinders. Theindustrial chain 106, which may be connected to and lifts the bar 108,may travel vertically up the inside of track 102 to the top and thentravel over a sprocket (shown in FIG. 2). This may turn the sprocket,for example, 90 degrees so that industrial chain 106 can travelhorizontally along the cylinder where it may encircle another sprocketconnected to the piston end of the cylinder. The end of chain 106 maythen connect to the body of the cylinder.

FIG. 2 illustrates an embodiment of a shaft used in embodiments of theinvention. Shaft 130, known as the lateral transverse or jack shaft, mayextend across the width of the rear of the trailer. On each end of thatshaft 130 may be a sprocket 132. Roller chain 106 which connects thehorizontally mounted hydraulic cylinders 104 to the slide bar 108 maypass over each sprocket. Because the sprockets 132 may be connected viashaft 130, one sprocket 132 cannot move without its counterpart on theother end moving. Thus, the movements of chains 106 are alwayssynchronized and this prevents one side of platform 110 from gettingahead of the other side and causing a “wedge” or jam, which, when anautomobile is sitting on platform 110, is a major problem to fix.

When a chain travels 180 degrees around a sprocket 132, for each footthat sprocket 132 moves, the free end of the chain may move two feet.Therefore, for each foot the horizontal cylinder pistons move forward,liftgate 110 may rise two feet. This allows the cylinders to be muchmore compact, less complex and weigh less. Embodiments of the inventionmay utilize gear motors to turn the shaft.

Returning to FIG. 1, in embodiments of the invention, there may be threesets of chains at work. One set of chains are the previously describedindustrial roller chains 106 inside track 102 which may lift bar 108 andhinge point 116 of liftgate 110. Another set of chains may includestandard short “link” static chain 112 which may be affixed to the topof the bar 108 and to liftgate 110, for example, about seven feet downfrom the top of liftgate 110. When liftgate 110 is closed, it may besupported by the affixed link chains 112. A third set of chains mayinclude longer link chains 114 which may be connected to the top of theroller bar 106 on one end and mid-way along liftgate 110 on the otherend, thereby creating diagonal support.

The embodiment illustrated in FIG. 1 shows the liftgate apparatus justas liftgate 110 begins to open. The hydraulic cylinders 104 may be usedto raise the liftgate's hinge point 116 via industrial roller chain 106.When the piston in the top horizontal hydraulic cylinder extends, anumber of things may happen simultaneously. First, as the hinge 116 andliftgate 110 move upward, this movement may release two sets ofmechanical latches. One latch set may be attached to a rain cap which,in the closed position, may extend over the top of liftgate 110. As thelatches release, torsion springs may rotate the cap, for example, 90degrees. Second, because liftgate 110 is vertically “balanced” on itshinge pivot in the closed position, as the top latches release, springloaded levers may “push” liftgate 110 outward at the top, beginning theinitial transition of liftgate 110 from a vertical position to ahorizontal position. Third, while the affixed link chains 112 are almostvertical when holding the liftgate closed, as the hinge point 116 ofliftgate 110 moves upward, this may create a slack in chains 112 whichallows the top of liftgate 110 to swing outward. As this continues,chains 112 may become more diagonal and may allow liftgate 110 tocontinue its rotation from a vertical to horizontal position. As hingepoint 116 and bar 108 continue to rise and liftgate 110 rotates to thefull horizontal position, for example, approximately nine feet aboveground level, longer affixed link chains 114 begin to tighten taking theload off the shorter affixed link chains 112.

FIG. 3 illustrates an embodiment of a rain guard/latch assembly used inembodiments of the invention. Note the top mounted nylon rollers 302which may be evenly spaced along the length of the cap. A single rollermay be placed at the end of a ten inch long flat piece of aluminumprotruding downward at an angle. When liftgate 110 closes, it may makecontact with this single extended roller first. The roller may be springloaded and as it is pushed inward, when the rain guard is in the openedposition, as shown in FIG. 3, the cams it is attached to may beginrotation of the latches to the “catch lock” position. As the liftgate110 continues inward, it next makes contact with smaller rollersattached to the cap which causes the rain guard cap to rotate to aclosed position and as it hits the stops, the latches may lock the gatein place.

When liftgate 110 rises vertically about two inches, via hydraulicpressure, it reverses this process with the cap rotating open and thespring loaded single rollers on the ten inch shafts (one on each side ofthe liftgate) pushing outward so the gate can swing out from under thecap and begin downward rotation. The benefit for a single owner/operatoris that this is all automatic and provides security, safety and aweather tight seal.

FIG. 4 further illustrates an embodiment of the liftgate apparatus,wherein liftgate 110 which is being opened is nearing full horizontal“platform” position. FIG. 4 shows features of an embodiment of theliftgate apparatus as seen from the left side of the rear of thetrailer. As the hinge point 116 or bottom of liftgate continues to rise,the “short” affixed chains 112 may still be supporting the top ofplatform/liftgate 110, but “long chains” 114 may become tighter, atwhich point short chains 112 will become loose.

FIG. 5 illustrates an embodiment of the liftgate apparatus whereinliftgate 110 is in a full horizontal “platform” position. At this point,with shorter link chains 112 loose, one end may be disconnected leavingliftgate 110 supported solely by the longer link chains 114 and theroller industrial chains 106 which supports bar 108 and hinge point 116.When liftgate 110 is in the full horizontal or “platform” mode, becausethe hinge and longer chains are connected to the moving bars, it may beraised or lowered as a horizontal platform by the hydraulic cylinders104 from the ground level to various deck levels. For example, in anembodiment of the invention, the elevator liftgate platform 110 can berun up and down from ground level to ten feet above ground level whileremaining horizontal. To move the elevator liftgate platform 110 up, anembodiment of the invention may use hydraulic power connected throughchains 106 inside the upright channels to horizontal cylinders 104hidden in upper horizontal structural aluminum members. Thus, inembodiments of the invention, the small totally hidden horizontalcylinders in the top structural members of the trailer are in sharpcontrast to the large vertical cylinders normally used which cause thetrailer to be longer.

FIG. 6 further illustrates an embodiment of the liftgate apparatuswherein liftgate 110 is in a full horizontal or platform position. Tallvertical channels 102 are shown on the right side, wherein a “slide bar”108 may be located in the channel 102. At the bottom of the protrudingslide bar 108, the base of platform 110 may be connected via a hinge 116which runs the full width of the trailer. At the top of the slide bar108, longer link chain 114 may be connected which extends to a pointabout eight feet out on the platform. When the cylinders up in the topof the trailer extend, they may pull on “roller chains” 106 which arehidden inside the vertical channels 102. Because the end of these rollerchains 106 may be connected to the ends of slide bar 108, as slide bar108 begins to move vertically, it moves the hinge point 116 of theplatform vertically and the longer link chains 114.

The slide bars 108 can extend below the vertical channels which allowthem to take the base or hinge part 116 of the horizontal platform 110right down to ground level. The slide bars 108 can also rise verticallyto upper deck levels, for example, about ten feet above ground level.Note that because of the “two to one” mechanical advantage of the upperlevel cylinders 104 and sprocket arrangement (described in FIG. 2) thehydraulic cylinders only have to extend five feet in order to raise theplatform 110 ten feet.

Once platform 110 reaches a predefined deck level, short chains 112 canbe reconnected to liftgate 110. As soon as the short chains areconnected, the balance or pivot point of the semi-balanced platform hasbeen moved closer to the trailer. This means that the base or hinge side116 of platform 110 is actually heavier than the other end. Therefore,when the hydraulic pressure is released, it tends to pivot toward thehinge side. Like a see-saw, when one side goes down, the other goes up.Thus, the liftgate platform 110 begins to rotate as hydraulic pressureis released. Because the hydraulic fluid can only pass through checkvalves at a slow controlled rate, as gravity pulls the base or hingeside 116 downward, it can only exert minimal pressure and move veryslowly, which is a safety factor. According to embodiments of theinvention, any resistance will stop the platform from moving.

As liftgate 110 nears the vertical or fully closed position, shortchains 112 may be also almost vertical and may support much of theweight of liftgate 110 along with the hinge 116 at the base. Thepositioning of short chains 112 on the framework of the trailer and onthe liftgate may enable steady and concise movement, as well as, theability to gently swing liftgate 110 shut in the last ten inches ofmovement. When this happens, the liftgate may trip a set of cams at thetop of the trailer. These cams may rotate the rain cap and latches intoposition, thereby locking the liftgate into the closed position. Theonly way to open the liftgate may be to activate the hydraulic cylindersand lift the gate vertically, at which time the cams may reverse, openthe latches, and rotate the rain cap up and out of the way as theliftgate 110 opens up.

Thus, embodiments of the present invention may utilize a two to onemechanical advantage with two top mounted horizontal double cylinders104 timed out or synchronized through a jack shaft 130. Embodiments ofthe inventive liftgate apparatus, therefore, may use gravity to bringliftgate 110 down to ground level and also close liftgate 110. Theclosing, latching, and rain cap features may enable the inventiveliftgate apparatus to be used without channel extensions extendingthrough the roof of the trailer and may cause the liftgate apparatus tobe operated by one person, without physically touching the liftgate.

FIG. 7 illustrates an embodiment of the invention, wherein liftgate 110is being prepared to be used as a ramp. By lowering liftgate 110 to theground level and disconnecting one end of the longer link chains 114,the hinge point 116 may be hydraulically lifted to the first deck level,thus creating a ground to first level ramp for loading. Key locks in theconnecting links may prevent inadvertent disconnection of these chains.The ramp may then be used, for example, to load a motorized vehicle,such as a 30′ long boat. One person may therefore place the inventiveliftgate apparatus in the ramp position. As the population ages,embodiments of the invention advantageously allows anyone to safelyadjust the liftgate and operate the liftgate apparatus with a handheldremote control unit.

FIG. 8 illustrates an embodiment of the liftgate apparatus, whereinliftgate 110 is being closed. To close liftgate 110, the short chains112 are reattached. It should be noted that the longer chains 114 arealso attached. The liftgate apparatus also may include a remote controlwith a button for releasing hydraulic pressure. Since the gate is“balanced”, i.e., the base is slightly heavier than the other end, asthe hydraulic fluid bleeds off, gravity pulls hinge point 116 downwardvery gradually and the platform 110 begins to rotate toward vertical.This movement continues until the hinge point 116 is at the lower decklevel. At this point, the gate may close completely and as it strikesthe cams on the hinged rain cap on top, the rain cap may rotate over theend of the gate and latches may become engaged automatically to preventthe gate from opening. Thus, when closing, liftgate 110 may rotate to afull closed position without assistance and, via cam action, the raincap may rotate, for example, 110 degrees from an open to a closedposition and may create a seal between the rain cap and the top of theliftgate. This provides unassisted opening and closing of the liftgate.

While all prior art screw type and slide bar liftgates must be “powereddown” by hydraulic force, the inventive liftgate apparatus is“balanced”, i.e., no hydraulic force is required to move liftgate 110from a horizontal to vertical position or to close it for transit.According to some embodiments of the invention, gravity alone allows theplatform to rotate from the horizontal to vertical position and gravityalone allows it to go to the fully closed position. The safety provisionof this feature becomes obvious when one considers that several tons ofdownward force can crush items or fatally injure people caught in thepath of a traditional descending liftgate while minimal pressure willstop the liftgate apparatus from descending and closing.

Although the present invention has been shown and described with respectto certain embodiments, it should be understood by those skilled in theart that various modifications can be made to the inventive liftgateapparatus and the method of operating the same of the instant inventionwithout departing from the scope and spirit of the invention. It isintended that the present invention cover modifications and variationsof the inventive testing device and method provided they come within thescope of the appended claims and their equivalents

1. A liftgate apparatus, comprising: a plurality of vertical tracksattached to a rear of a trailer, each of the plurality of verticaltracks including a vertical roller chain, wherein tops of the pluralityof vertical tracks intersect horizontal hollow structural tubes whichinclude hydraulic cylinders; at least one bar attached to a bottom ofeach vertical roller chain and attached to sets of rolling wheelsconfigured to move the at least one bar vertically inside the pluralityof vertical tracks; a plurality of hinges attached to a lower end of theat least one bar and attached to a base of a liftgate, wherein thevertical roller chain lifts the at least one bar and the liftgate athinged points; a plurality of types of link chains, wherein a first typeof the link chains supports the liftgate in a closed position and thefirst type is affixed to the top of the at least one bar and to theliftgate, and wherein a second type of the link chains is affixed to thetop of the vertical roller chain and to mid sections of the liftgate;and a plurality of sprockets connected via a shaft, wherein the verticalroller chain travels over at least one of plurality of sprockets andconnects the hydraulic cylinders to the least one bar, thereby movingthe at least one bar and the attached liftgate in a synchronized manner.2. The apparatus of claim 1, wherein one of the plurality of verticaltracks is on one end of the trailer and another of the plurality ofvertical tracks is on another end of the trailer.
 3. The apparatus ofclaim 1, wherein when traveling over at least one plurality ofsprockets, the vertical roller chain turns the sprocket so that thevertical roller can travel horizontally along the cylinder where itencircles another sprocket connected to a piston end of the hydrauliccylinders.
 4. The apparatus of claim 3, wherein when the liftgate isopening, the piston extends and moves the hinged points and liftgateupwards.
 5. The apparatus of claim 4, wherein the upward movement of thehinged points and liftgate releases mechanical latches, one of which isattached to a rain cap which extends of the top of the liftgate in aclosed position, wherein release of the latches pushes the top ofliftgate outward and begins initial transition of the liftgate from avertical position to a horizontal position.
 6. The apparatus of claim 4,wherein the upward movement of hinged points and liftgate causes thefirst type of the link chains which supports the closed liftgate tobecome slack and allow the liftgate to swing outward and continue torotate from a vertical position to a horizontal position.
 7. Theapparatus of claim 4, wherein the upward movement of hinged points andliftgate causes the second type of the link chains to tighten andsupports the load of the liftgate.
 8. The apparatus of claim 1, whereinthe shaft extends across the width of the rear of the trailer and gearmotors are used to turn the shaft and wherein the sprockets move at aslower rate than the liftgate at the other end of the vertical rollerchain.
 9. The apparatus of claim 1, wherein when the liftgate is in afull horizontal position, the first type of the link chains may bedisconnected from the liftgate, leaving the liftgate supported by thesecond type of the link chains and the vertical roller chain.
 10. Theapparatus of claim 1, wherein when the liftgate is in a full horizontalposition, the liftgate is raised or lowered as a horizontal platform bythe hydraulic cylinders connected through the vertical roller chain. 11.The apparatus of claim 1, wherein the hydraulic cylinders are hidden inthe horizontal hollow structural tubes.
 12. The apparatus of claim 1,wherein the liftgate begins to rotate from a horizontal position to avertical position when hydraulic pressure is released.
 13. The apparatusof claim 12, wherein resistance applied to the liftgate prevents themovement of the liftgate from the horizontal position to the verticalposition due to the rate in which the hydraulic pressure is released.14. The apparatus of claim 1, wherein when the liftgate is almost in afull vertical position, the positioning of the first type of the linkchains enable the liftgate to be shut.
 15. The apparatus of claim 1,wherein when the liftgate is closed, the liftgate trips a set of cams onthe top of the trailer, wherein the cams rotate a rain cap and latchesinto position to lock the liftgate in a closed position.
 16. Theapparatus of claim 1, wherein when the liftgate is in a full horizontalposition at ground level, the second type of the link chains may bedisconnected from the liftgate and hinge points may be hydraulicallylifted to a deck level of the trailer, thus creating a ground to decklevel ramp.
 17. The apparatus of claim 1, further comprising a remotecontrol for releasing hydraulic pressure.
 18. A method of opening andoperating a liftgate of an apparatus, comprising: releasing a set ofmechanical latches via a plurality of sprockets connected via a shaft,wherein vertical roller chains travel over at least one of plurality ofsprockets and connect hydraulic cylinders to least one bar configured tomove the liftgate into a horizontal position; engaging the hydrauliccylinders and pushing the liftgate outward at the top by levers whichare activated as the latches are released; as the liftgate moves into ahorizontal position, slackening a first set of link chains whichsupports the liftgate in a closed position and which is affixed to thetop of the at least one bar and to the liftgate; tightening a second setof link chains affixed to the top of the vertical roller chains and tomid sections of the liftgate as the liftgate reaches the horizontalposition; and moving the liftgate using the hydraulic cylinders.
 19. Amethod of closing a liftgate of an apparatus, comprising: verticallymoving the liftgate and attaching a first set of link chains whichsupports the liftgate in a closed position and which is affixed to thetop of at least one bar and to the liftgate, wherein the bar isconnected to the liftgate via hinged points; releasing hydraulicpressure via vertical roller chains which are attached to the at leastone bar to cause the liftgate to move from a horizontal position to avertical position; and upon the liftgate reaching a vertical position,tripping latches and a rain cap into position to prevent the liftgatefrom opening.